Feto-maternal Outcome Using New Screening Criteria of Serum TSH for Diagnosing Hypothyroidism in Pregnancy.

INTRODUCTION Evidence suggests that by using the classical non pregnant reference range for serum TSH (STSH), one might miss hypothyroidism in pregnancy. Therefore, upper normal cut off value of S TSH should be taken as <2.5 mIU/L in the first trimester and <3mIU/L in the second and third trimester. However, two Indian studies have reported higher trimester specific reference ranges in the Indian pregnant women. OBJECTIVES To assess the maternal and fetal outcomes using new screening criteria with upper S TSH cut off as >3mIU/L, for diagnosing hypothyroidism in pregnancy. MATERIALS AND METHODS This study was a cross sectional study, carried out in the Department of Obstetrics and Gynaecology of a tertiary care hospital, in collaboration with the Department of Endocrinology. Pregnant women with ≤ 20 weeks gestation, attending antenatal OPD from December 2010 to January 2012 were included in the study. On the basis of S TSH level, women were divided into Study Group with S TSH level between 3.1 to 6.2 mIU/L, (new range to be studied) and an equal number of age and parity matched Control Group with S TSH levels between 0.4 to 3 mIU/L. The maternal and fetal outcomes were compared between study and control groups. RESULTS During the study period, a total of 66 women had S TSH between 3.1-6.2 mIU/L. Maternal and fetal outcomes in both the groups were comparable. There was no difference in the mode of delivery between study and control groups. CONCLUSION The lower S TSH cut off recommended for diagnosing hypothyroidism in pregnancy may not be applicable to pregnant Indian women.